Linking Fundamental Investigations and Engineering Results for Extinguishment of Fires on Solid Material

Vlachos CTS-9710413这是一项关于固体材料上火焰熄灭的研究，因为反馈到表面的能量要么通过表面的直接冷却，要么通过热或化学试剂使氧化剂气流惰化而减少。本研究使用现代延拓方法对化学反应体系中的定态溶液进行数值计算。数值结果用一种新的灵敏度分析、简单的火焰熄灭物理模型和标准的渐近分析来解释。通过在恒温下用多孔气体燃烧器模拟热解物质，将气体燃烧动力学与表面能量平衡分离，其中甲烷或乙烯等燃料与氧化剂流动一起燃烧。研究的一个问题是，当灭绝的关键条件，如无因次燃料供应，与达科勒数无关时。通过化学惰性或活化剂对燃料和/或氧化剂流的各种稀释物和各种应变率的质量供应速率的函数来计算反馈到表面的火焰热。包括对流和辐射热反馈。灭火的经验方法从史前时代就开始使用了。在过去的三十年里，已经开发出了复杂的气体火焰消光模型，但几乎没有什么模型可以应用于固体表面的火焰。大多数实际感兴趣的固体材料的热解化学细节尚不清楚。目前，还没有一个通用的、稳健的策略来描述在各种环境气流和环境条件下固体火灾的熄灭。这个项目概述了这样一种策略；它将最先进的流体相和化学模型以及非线性系统理论与现有的实验数据和消光测量技术相结合。

Abstract - Vlachos CTS - 9710413 This is an investigation of flame extinction of fires on solid materials occurring because the energy feedback to the surface decreases either by direct cooling of the surface or by inerting of the oxidant stream by a thermal or chemical agent. The study uses modern continuation methods for numerical calculation of stationary-state solutions in chemical reaction systems. Numerical results are interpreted with a novel sensitivity analysis, simple physical models for flame extinction, and standard asymptotic analysis. Gaseous combustion dynamics is separated from the surface energy balance by simulating the pyrolyzing material with a porous gaseous burner at a constant temperature in which a fule such as methane or ethylene burns with the oxidant flow. One isssue examined is when critical conditions for extinction, such as dimensionless fuel supply, are independent of the Damkohler number. The flame heat feedback to the surface is calculated as a function of mass supply rate for various dilutions of the fuel and/or oxidant streams by chemically inert or active agents and for various strain rates. Both convective and radiative heat feedback are included. Empirical methods for extinguishing fires have been used since prehistoric times. In the last thirty years, sophisticated models for extinction in gaseous flames have been developed, but little of this can be applied to fires on solid surfaces. Details of pyrolysis chemistry for most solid materials of practical interest are unknown. At present, no general, robust strategy exists to characterize extinction of solid fires under varioius ambient flow and environmental conditions. Such a strategy is outlined in this project; it integrates state-of-the-art fluid-phase and chemistry models and nonlinear systems theory with available experimental data and measurement techniques for extinction.